1. Field of the Invention
The present invention relates generally to printing inks and, more particularly, but not by way of limitation, to a vegetable oil-based printing ink for lithographic printing presses.
In one aspect, the present invention relates to a method of reclaiming residual vegetable oil-based printing ink from a printing press during the cleaning of a printing press by recovering residual vegetable oil-based printing ink from printing presses and utilizing such recovered residual vegetable oil-based printing ink in the formulation of the vegetable oil-based printing ink.
In another aspect, the present invention relates to a method for polymerizing a vegetable oil component of such vegetable oil-based printing ink.
2. Brief Description of the Prior Art
Printing ink produced in the past has been petroleum-based, typically comprised of 15-20% carbon black as the pigment, 15-25% hydrocarbon or alkyd resin, and 50-70% mineral oil solvent. Nearly 500 million kilograms of inks for these applications are produced domestically each year. This volume of production represents a substantial consumption of petroleum-based ingredients. The petroleum oil shortage in the mid-1970's stimulated research to find alternatives to mineral oil and other petroleum products in ink formulations.
In the early 1980's, the American Newspaper Publishers Association ("ANPA") directed a research effort on developing a non-petroleum-based vehicle for newspaper inks. In response to the ANPA directives, numerous approaches were taken resulting in the formulation of vegetable oil-based ink using a combination of petroleum based ingredients and soy bean oil. Widespread commercial acceptance of the petroleum based/soy bean oil ink has been inhibited, however, by the cost, which is 50-70% more than traditional petroleum-based black inks. Additionally, although these inks tout the 100% soy bean oil ingredient, petroleum derivatives are still added to the formulation of the ink to achieve certain characteristic standards.
Despite these advances made by the ANPA and others, the industry has continued to seek a non-petroleum-based printing ink which would "(1) be cost competitive with petroleum-based inks; (2) not require any petroleum-derived component; (3) resist ruboff on hands and clothing; and (4) enable formulation over a wide range of viscosities required by various printing applications.
In 1991, U.S. Pat. No. 5,122,188 was granted wherein Nitrogen was employed to produce a 100% vegetable oil-based printing ink with no petroleum derivatives. Problems have been encountered in employing the non-petroleum derivatives when scaling up for commercialization of the process. The problems that persist in the use of vegetable oil-based inks for lithographic printing presses include lengthy drying time, environmental waste concerns, high production costs, difficulty in clean up, and high material costs.
The present invention solves the above problems that exist in prior vegetable oil-based printing inks by providing a vegetable oil-based printing ink system that lowers material and production costs. Additionally, the vegetable oil-based printing ink is recyclable and removable directly from the printing presses for reuse as a component in the formulation of the vegetable oil-based printing ink. A significant benefit in the current invention is the ability to polymerize vegetable oil in the same process to form high quality recyclable vegetable oil-based printing inks having a wide range of viscosities. The vegetable oil-based printing ink eliminates dependance on petroleum products and provides competitive performance characteristics.